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At least 1,567 records · Page 87Linked to original sources
PubMed1992

The catecholamine-mediated positive inotropic effect of simple quinones is related to superoxide anion generation.

In guinea pig and rat cardiac tissue, redox cycling benzoquinones (2,5-dimethyl-p-benzoquinone and duroquinone) and naphthoquinones (menadione and 2,3-dimethoxy-1,4-naphthoquinone) generated superoxide anion (O2-.) both through one- and two-electron reductions, the generation being significantly greater in guinea pig than in rat tissue. In electrically driven left atria isolated from guinea pig and rat, menadione and 2,5-dimethyl-p-benzoquinone but not duroquinone caused a concentration-dependent positive inotropic effect. Unlike guinea pig, 2,3-dimethoxy-1,4-naphthoquinone had no effect in rat tissue. Naphthoquinones and 2,5-dimethyl-p-benzoquinone were more active in guinea pig than in rat tissue, their effect being dependent on the release of catecholamines from adrenergic stores. A linear relationship (r = 0.90) between the amount of O2-. generated by benzo- and naphthoquinones in guinea pig and rat heart and the extent of catecholamine-dependent positive inotropic effect was evident. An amount of O2-. higher than 600 nmol/g of tissue per min was calculated to be necessary to determine the catecholamine-mediated increase in contractility. Lipid peroxidation was not involved in quinone-induced catecholamine release.

Animals↗
PubMedDate not supplied

Changes in serum catecholamine levels in patients who are brain dead.

Prospective blood samplings from 15 patients admitted with a Glasgow Coma Score of less than 7 were obtained to observe and compare epinephrine, norepinephrine, and dopamine serum levels in patients with brain injury before, after, and in the absence of brain death. Nine of the patients developed or were admitted after brain death. Wide variations in catecholamine blood levels over time were documented, and subgroup analysis precluded useful statistical comparison or inference of the data. The data are presented therefore as descriptive observations only. No apparent differences were noted between similarly injured patients in whom brain death did not develop and patients before brain death or between patients with penetrating versus nonpenetrating brain injury. Brain death was preceded by hypertension and corresponding elevations in serum catecholamine levels in one patient with complete data. Catecholamine levels appeared to fall after brain death in most patients. Only minimal changes in myocardial histology were present in three donor hearts, and the two transplanted hearts functioned satisfactorily. Serum catecholamine measurement or monitoring does not provide a precise method of determining potential injury to the donor heart before or after brain death. Other experimental data and clinical observation indicate that some hearts may be injured in the donor during the evolution of brain death. Pharmacologic intervention may prevent such injury in experimental animals but must be used before brain death is induced. Such interventions should be studied in selected human donors before brain death to determine whether cardiac function is improved in the donor or recipient.

Adult↗
PubMed2003

[Effects of catecholamines on human preadipocyte proliferation and differentiation].

OBJECTIVE: To study the effects of catecholamines on human preadipocyte proliferation and differentiation. METHODS: Catecholamines (epinephrine, isoprenaline and noradrenaline) were added to the culture media of human preadipocytes. The proliferation of cells, the expression of GPDH and lipid droplet accumulation in cytoplasm were observed and recorded. The functions of alpha and beta receptors were examined with adding alpha and beta receptor blockers. RESULTS: Epinephrine and isoprenaline stimulated human preadipocyte proliferation and inhibited GPDH up-regulation during differentiation. The three types of catecholamines inhibited lipid accumulation in cell differentiation. The beta-adrenoceptors played a key role during the process. CONCLUSION: Human preadipocytes responded to catecholamine characteristically. The result would be applicable in the study of drugs for obesity.

Adipocytes↗
PubMed1992

Differential effects of 6-hydroxydopamine-induced ablation of peripheral and central adrenergic axons on C-1300 murine neuroblastoma tumor growth and catecholamine concentration in the A/J mouse.

The relationship between 6-hydroxydopamine (6-OHDA)-induced ablation of central and peripheral adrenergic neurons and in situ C-1300 murine neuroblastoma (MNB) tumor growth and catecholamine concentration were investigated. Destruction of central and/or peripheral adrenergic neurons was produced by the intracerebral and/or s.c. administration of 6-OHDA to neonatal A/J mice. Disaggregated MNB cells (1 x 10(6)) were implanted s.c. into each mouse 3 weeks after treatment with 6-OHDA or diluent. Tumor onset time (the time interval between implantation of MNB cells and detection of palpable tumor), tumor weight, tumor weight to body weight ratio, tumor growth rate constant and tissue catecholamine concentrations were determined. Central axotomy caused a significant increase in tumor onset time and decrease in tumor weight when compared to controls. However, neither the tumor weight to body weight ratio or tumor growth rate constant were significantly lowered. In contrast, a reduction in all tumor growth parameters was produced by peripheral axotomy, which differed significantly from centrally axotomized and control animals. The catecholamine concentration of MNB tumors excised from control and 6-OHDA-treated mice 8 days after tumor onset were determined. Norepinephrine and dopamine levels were elevated above controls in MNB tumors obtained from mice that had been either peripherally or peripherally and centrally axotomized; whereas, no change in tumor catecholamine concentrations was noted in centrally axotomized mice. This investigation has demonstrated that ablation of central as well as peripheral adrenergic innervation exerts an inhibitory effect on MNB tumor growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Trichosporin-B-III, an alpha-aminoisobutyric acid-containing peptide, causes Ca(2+)-dependent catecholamine secretion from adrenal medullary chromaffin cells.

We examined the effect of trichosporin-B-III, an alpha-aminoisobutyric acid-containing antibiotic peptide consisting of 19 amino acid residues and a phenylalaninol, on catecholamine secretion from cultured bovine adrenal chromaffin cells. Incubation of the cells with trichosporin-B-III (3-20 microM) caused an increase in the secretion of catecholamines. The secretion induced by trichosporin-B-III at low concentrations (3 and 5 microM) was completely dependent on external Ca2+, whereas that induced by higher concentrations (10 and 20 microM) was partly independent of Ca2+. Trichosporin-B-III at low concentration (5 microM) did not increase the release of lactate dehydrogenase, a marker enzyme of cytoplasm, from the cells. In contrast, the peptide at higher concentration (10 microM) increased the release of the enzyme. Trichosporin-B-III also caused both 45Ca2+ influx into the cells and an increase in the intracellular free Ca2+ concentration. The increases in catecholamine secretion and 45Ca2+ influx behaved similarly in relation to trichosporin-B-III concentration (3-10 microM). The time courses of the increases in secretion, 45Ca2+ influx, and intracellular free Ca2+ concentration induced by trichosporin-B-III were also quite similar. Trichosporin-B-III-induced (at 5 microM) secretion was not affected by the elimination of Na+ from the incubation medium or by the addition of tetrodotoxin, a blocker of highly selective voltage-dependent Na+ channels, or hexamethonium, a blocker of nicotinic acetylcholine receptors. On the other hand, both diltiazem (2-200 microM) and nicardipine (1-200 microM), blockers of voltage-dependent Ca2+ channels, inhibited the secretion induced by trichosporin-B-III (5 microM) in a concentration-dependent manner. Trichosporin-B-III-induced (at 5 microM) secretion also was suppressed by the addition of Mn2+ (5 mM) to the medium. The diltiazem (20 microM) inhibition of trichosporin-B-III-induced (at 5 microM) secretion was reversed by increasing the external Ca2+ concentration. These results indicate that trichosporin-B-III causes the secretion of catecholamines from bovine adrenal chromaffin cells by two mechanisms, Ca2+ dependent and Ca2+ independent (only at high concentrations of trichosporin-B-III). Furthermore, these results strongly suggest that trichosporin-B-III, in Ca(2+)-dependent secretion, activates endogenous voltage-dependent Ca2+ channels, or itself forms the channels in the membranes, and induces Ca2+ influx into the cells.

Adrenal Medulla↗
PubMed1991

Effects of dopamine receptor agonists and antagonists on catecholamine release in bovine chromaffin cells.

Dopamine D2 receptors are known to regulate the release of catecholamines from neurons in the central and peripheral nervous systems. In the present study we have evaluated the effects of dopamine D2 agonists and antagonists on the release of endogenous norepinephrine and epinephrine stimulated by 50 microM nicotine in isolated bovine chromaffin cells in order to investigate whether isolated bovine chromaffin cells may contain functional dopamine D2 receptors. Dopamine (10(-4) and 10(-6) M), quinpirole (10(-5) M) and 2-amino-5,6-dihydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide (10(-5) M) had no effect on the nicotine-stimulated release of norepinephrine or epinephrine from the bovine chromaffin cells. Pergolide (10(-6) M) and apomorphine (10(-4) M) produced a significant inhibition of nicotine-stimulated release of both norepinephrine and epinephrine from the chromaffin cells. The inhibitory effect of the selective dopamine D2 agonist pergolide on catecholamine release from the chromaffin cells was not reversed by 10(-6) M concentrations of the selective dopamine D2 receptor antagonists haloperidol, domperidone, metaclopramide, fluphenazine, flupentixol, (+)- or (-)-sulpiride, the dopamine D1 receptor antagonist SCH 23390 (10(-7) M) or the alpha receptor antagonist phentolamine (10(-6) M). These data suggest that the inhibition of nicotine-stimulated release of catecholamines from the bovine chromaffin cells is not a receptor-mediated effect. Further studies showed that the inhibitory effect of pergolide on catecholamine release in the bovine chromaffin cells was correlated with an inhibition of nicotine-stimulated 45Ca++ uptake and 22Na+ uptake into these cells. It is concluded that functional dopamine D2 receptors of the classical type do not exist on isolated bovine chromaffin cells.

Animals↗
PubMed1990

[Determination of free catecholamines in the urine using high efficiency liquid chromatography with an electrochemical detector].

The authors describe electrochemical detector high-pressure liquid chromatography (EDHPLC) technique for measuring nanogram amounts of catecholamines in human urine. Alumina-treated samples are layered onto a reverse-phase column for the separation of catecholamines, with a monochloracetate buffer/acetonitrile mixture containing 75 mg of sodium octyl sulfate as the mobile phase. Electrochemical detector was employed for the quantitative detection of catecholamines. Catecholamine levels of up to 1000 ng are detectable with the use of electrochemical detector. EDHPLC is a highly suitable method for clinical investigations.

Catecholamines↗
PubMed2006

An appraisal of selection and use of catecholamines in septic shock - old becomes new again.

The use of catecholamines to defend and resuscitate patients with septic shock remains a cornerstone of intensive care medicine. The pharmacological support of the failing circulation during sepsis and septic shock should be directed at augmenting perfusion of vital organs and facilitating venous return, rather than peripheral arterial vasoconstriction. There appears to be a teleological rationale for primary use of catecholamines to augment failing endogenous neurohumoral and neuroendocrine cardiovascular systems. To this end, it seems intuitive to use the predominant naturally occurring catecholamine, noradrenaline, as the first-line agent for circulatory failure, although there are no definitive clinical trials to support this. Adrenaline has an established place in many parts of the world, particularly low-income countries, and appears to be equivalent to noradrenaline for reversing septic shock. There is increasing evidence for adverse neuroendocrine and immunological effects of dopamine, warranting circumspection about its use. The use of synthetic inotropes and vasopressors for septic shock remains limited, with little biological rationale. Clinicians should wait for definitive outcome-based trials of these expensive agents before incorporating them into practice. Supplemental endocrine replacement therapy with low-dose corticosteroids and vasopressin appears biologically plausible and has an emerging role. Results of large-scale, high-quality trials of endogenous catecholamines for sepsis and septic shock are awaited. These may provide additional, important information for evidence-based guidelines, which currently remain of limited clinical utility.

Cardiovascular System↗
PubMed1992

Affinity of different local anesthetic drugs and catecholamines for the contraluminal transport system for organic cations in proximal tubules of rat kidneys.

To study the cellular uptake of [3H]tetraethylammonium (TEA) and its inhibition by different local anesthetic drugs and catecholamines, the capillary stopped flow microperfusion method was used. [3H]TEA concentration in the peritubular capillaries decreased in a time and concentration-dependent manner. This cellular uptake of [3H]TEA could be described by a facilitated diffusion model (Jmax = 0.57 +/- 0.08 pmol sec-1 cm-1, Km = 0.28 +/- 0.01 mmol/l). Between the pKa values of the local anesthetic drugs (range, 2.8-8.9) and their apparent Ki values, a significant correlation was found (r = -0.916, n = 12). In the case of catecholamines, hydrophobic substitution in the form of an alkyl chain in the alpha-position or at the nitrogen increased the inhibitory potency, whereas hydroxyl substitution in the beta-position decreased the affinity. Except for the catecholamines with complex substitutions at the benzene ring (--CH2OH,--NHCONH2,--OOCN[CH3)2, --Cl, --NH2) the apparent Ki values of the catecholamines were directly correlated with the hydrophobicity. It is concluded that hydrophobicity and pKa are two important physicochemical parameters which influence the affinity of a molecule for the transport system for organic cations at the contraluminal side of renal proximal tubules.

Anesthetics↗
PubMedDate not supplied

Catecholamine-mediated elevation of cyclic GMP in the rat C-6 glioma cell line.

Catecholamines cause an elevation of both cyclic GMP and cyclic AMP levels in the rat C-6 glioma cell line. The response is mediated by a beta-receptor, with a Ka for stimulation of cyclic GMP of 2.6 X 10(-7)M. Maximum levels of cyclic GMP are reached by 5 min. whereas cyclic AMP levels are maximal by 10 min. Removal of calcium decreases the cyclic GMP elevation by 60%. Refractoriness to a second treatment with catecholamine develops for both responses. Catecholamine sensitivity of the cyclic GMP-generating system appears in the cells only as they start to contact and enter the stationary growth phase. In contrast to the effects of catecholamines, cholinergic agonists have no effect on either cyclic GMP or cyclic AMP levels.

Animals↗
PubMedDate not supplied

Changes in plasma catecholamines and pulsatile patterns of gonadotropin release in subjects with a normal ovulatory cycle and with polycystic ovary syndrome.

Plasma LH levels in women and female laboratory animals fluctuate. Since catecholamines play a role in gonadotropin secretion, we investigated the possible correlation between catecholamine metabolites and pulsatile patterns of gonadotropin release by measuring two catecholamine metabolites, MHPG and DOPAC. LH levels had a pulsatile pattern, and the levels of MHPG fluctuated. The average of LH and MHPG in polycystic ovary syndrome was significantly higher than that of a normal ovulatory cycle, and the average fluctuation of LH and MHPG in polycystic ovary syndrome was also significantly greater than that in a normal ovulatory cycle. There may be a correlation between the pulsatile pattern of gonadotropin and catecholamine activity, particularly adrenergic activity. It is suspected that adrenergic activity may correlate with the pulsatile pattern in polycystic ovary syndrome.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1979

Effects of acute and continuous morphine administration on catecholamine-sensitive adenosine triphosphatase in mouse brain.

The catecholamine-stimulated adenosine triphosphatase (ATP-ase) activities in mouse brain synaptosomes were inhibited by morphine both in vitro and in vivo. Morphine up to 10(-3) M had no effect on basal ATPase activities but at 10(-4) M significantly inhibited dopamine-sensitive ATPase activities in vitro. The morphine effect was antagonized by an opiate antagonist, naloxone. The catecholamine-sensitive ATPase activities were also inhibited by acute administration of morphine. The inhibition was dose-dependent. However, naloxone partially antagonized the morphine inhibition of depamine-sensitive ATPase activity but not norepinephrine-sensitive ATPase activity. A significant decrease in the sensitivity of synaptosomal ATPase to catecholamines was observed in mice rendered tolerant by morphine pellet implantation. The Na+,K+-ATPase was more affected by morphine as compared to Mg++-ATPase activity. The dopamine-sensitive Na+,K+-ATPase activity was restored by 50% in precipitated withdrawal mouse brain synaptosomes. Norepinephrine-sensitive ATPase activity was also restored partially in precipitated withdrawal animals. These results suggest that in mouse brain synaptosomes morphine may be interacting with ATPase at or near the catecholamine-active sites.

Adenosine Triphosphatases↗
PubMed1990

[Catecholamines in adrenergic nerve fibers of the lymph nodes after sympathectomy].

Using Falck method in combination with microfluorimetry, catecholamine level in adrenergic nervous fibers has been measured in the canine popliteal lymph nodes, normal and in 12 h, 7, 30, and 90 days after unilateral lumbar sympathectomy. During first 24 h after the operation the level of catecholamines is for certain increased in the nervous fibers of the lymph node of the sympathectomized extremity. In 30 days after the sympathectomy their content drops at the side of the operation and increases in the contralateral extremity. By 3 months the equilibrium of the catecholamine content is restored in the nervous fibers of the lymph nodes in the homo- and contralateral extremities at the level higher than in the control. A conclusion is made that under conditions of unilateral sympathectomy only a partial sympathectomy of the popliteal lymph node is reached. All luminiscent adrenergic nervous fibers of the sympathectomized lymph node are processes of neurons, situating in the contralateral sympathetic trunk, or neurites of cells in sacral nodes, getting their preganglionic fibers from the contralateral trunk. The changes in catecholamine concentrations mentioned are considered as a compensatory reaction, directed to maintenance of general homeostatic equilibrium under conditions, when the nervous system transfers to a new level, ensuring the partly desympathized tissue by mediators.

Adrenergic Fibers↗
PubMed1986

Catecholamine, serotonin, and substance P-like peptide containing intrinsic neurons in the mudpuppy parasympathetic cardiac ganglion.

The mudpuppy cardiac ganglion contains 2 neuron types: large parasympathetic postganglionic projection neurons and smaller intrinsic neurons originally described by McMahan and Purves (1976) as intensely fluorescent (SIF) cells. The function of these SIF cells, present in the mudpuppy cardiac ganglion, is unknown. Further, direct application of catecholamines, which are thought to be contained in SIF cells, to the parasympathetic postganglionic cells has no effect (Hartzell et al., 1977). As SIF cells in other ganglion preparations recently have been shown to contain putative transmitter substances in addition to catecholamines, immunocytochemical experiments were conducted to test for the presence of additional transmitter substances in the SIF cells within the cardiac ganglion. Whole-mount septal preparations were dissected from Necturus maculosus and processed for indirect immunocytochemistry. The results indicated that many of these intrinsic neurons contained 5-HT or a substance P-like peptide, or both. Many small intrinsic neurons which contain either substance P or 5-HT were also positive for aqueous-aldehyde-induced fluorescence, indicating the presence of a catecholamine. Finally, some of these cells appeared to contain all 3: a catecholamine, 5-HT, and a substance P-like peptide.

Animals↗
PubMed1989

Differential regulation of fat cell beta-2 and beta-1 adrenoceptors by endogenous catecholamines in dog.

The effects of long-term endogenous catecholamine exposure on the regulation of leukocyte and adipocyte beta adrenoceptor subtypes were studied through an experimental model of chronic neurogenic hypertension in the dog. Chronic sinoaortic denervation (SAD) is associated with a significant increase in plasma catecholamine levels, a reduction in the total beta adrenoceptor number of the leukocytes (52%) as well as of the omental adipocytes (59%). Using highly selective beta antagonists (bisoprolol for beta-1; ICI 118,551 for beta-2 adrenoceptors) we demonstrate that the normal dog fat cell possess both beta-2 and beta-1 adrenoceptors in proportions of 67 and 33%, respectively. SAD-induced catecholamine enhancement promotes a strong reduction of beta-2 (but not beta-1) adrenoceptor number (from 237 +/- 28 to 52 +/- 13 fmol/mg of protein) leading to a new relative distribution in fat cell membranes: 36% for beta-2 and 64% for beta-1 adrenoceptors. Such a different regulation provokes major consequences in the associated-biological effect on adipocytes when evaluating the lipolytic process. Lipolysis induced by epinephrine or isoproterenol (two mixed agonists) is weakly but significantly reduced whereas lipolysis induced by procaterol (a highly selective beta-2 agonist) is strongly reduced. These data fit with the results of the binding studies and demonstrate the loss in beta-2 adrenoceptor number and efficiency in SAD dogs. The present study demonstrates a differential regulation of beta adrenoceptors: beta-2 but not beta-1 adrenoceptors are decreased by long-term exposure to high plasma levels of endogenous catecholamines in the dog.

Adipose Tissue↗
PubMed1989

Ultrastructural basis for interactions between central opioids and catecholamines. II. Nuclei of the solitary tracts.

Interactions between central opioids and catecholamines are thought to underlie the ability of adrenergic agonists both to lower blood pressure and alleviate certain symptoms of opiate withdrawal. We examined the cellular substrate for interactions between neurons containing enkephalin-like opioid peptides and catecholamines in cardiovascular portions of the medial nuclei of the solitary tracts (m-NTS) of adult rats. Single sections were dually labeled using a double-bridged peroxidase method for the localization of a monoclonal leucine (Leu5)-enkephalin-antibody and immunoautoradiography for the localization of polyclonal antibodies against the catecholamine-synthesizing enzyme tyrosine hydroxylase (TH). Light microscopy revealed a few perikarya and numerous varicosities containing Leu5-enkephalin-like immunoreactivity (LE-LI). These were distributed among TH-labeled perikarya and processes throughout the rostrocaudal NTS. Electron microscopy of the m-NTS at the level of the area postrema further established the single as well as dual localization of TH and LE-LI in individual perikarya, dendrites, and axon terminals. Silver grains indicative of TH-labeling were usually distributed throughout the cytoplasm, whereas the peroxidase reaction product for LE-LI was localized principally to large (80-150 nm), dense-core vesicles. Immunoautoradiographic labeling for TH was detected in 118 terminals within a series of sections containing 183 terminals with LE-LI. Of these, 26% of the TH-labeled terminals and 32% of the enkephalin-containing terminals formed symmetric synapses with unlabeled dendrites, while only 7% of each type formed symmetric synapses with TH-labeled dendrites. In favorable planes of sections, the unlabeled as well as TH-labeled dendrites received convergent input from both types of terminals. A few of the remaining terminals that contained either TH or LE-LI formed asymmetric junctions with unlabeled distal dendrites; the others were without recognizable synaptic specializations within the plane of section. Approximately 20% of the TH-labeled terminals and 6% of the terminals containing LE-LI were dually labeled for both antibodies. These were invested with astrocytic processes characterized by bundles of intermediate filaments. We conclude that within cardiovascular portions of the m-NTS, opioid peptides and catecholamines contained within the same or separate terminals modulate the activity of target neurons through direct symmetric, probably inhibitory, synaptic junctions and may additionally modulate the activity of neighboring astrocytes through exocytotic release from large dense-core vesicles.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

[Solvent extraction and high performance liquid chromatography with electrochemical detection for determination of plasma catecholamines].

This paper describes a technique for selectively extracting plasma catecholamines prior to quantification by HPLC-EC. The extraction system was a two-stage process. The first stage involve the complex formation between diphenylbrorate and catechol (diol) groups in alkaline medium. The second stage was a liquid-liquid extraction. The complex combined with tetraoctylammonium bromide to form an ion-pair formation into organic solvent. The catecholamines in turn was extracted with acid. This technique provided a very specific extraction procedure which resulted in chromatograms with few interfering compounds and gave absolute recoveries (100-103%) of norepinephrine, epinephrine and dopamine. Meanwhile, the plasma catecholamines were concentrated and the detective sensitivity was increased. A good linear relationship was found between the concentrations and ratio of peak heights of the catecholamines from 0.125-2 ng. The correlation coefficients ranged from 0.998-0.999. The coefficients of variation of the intra- and inter-assay were within 3 and 6% respectively. The results show that the procedure is very simple and fast. The method is valuable not only for clinical diagnosis but also for laboratory research.

Catecholamines↗
PubMed1989

[The effect of prolonged exposure to gamma rays and hormonal stimulation with serum gonadotropin on the levels of catecholamines in the hypothalamus, epiphysis and adrenal glands in sheep].

The effect of the exposure of the whole body to continuous radiation and of the administration of serum gonadotropin (SG) was studied as exerted on the concentration of catecholamines (epinephrine and norepinephrine) in the hypothalamus, epiphysis and adrenal glands of ewes during the anoestric period with synchronized oestrus. The first group (young barren ewes) and second group (older ewes) were exposed to continuous radiation of 60Co for five days. The radiation was provided at the rate of 0.020 Gy per hour. After the termination of irradiation the ewes were subjected to hormonal stimulation by fractionated administration of 1500 I. U. SG. The third and fourth experimental groups of ewes were stimulated with 1500 I. U. SG without irradiation. Catecholamines were separated from the tissue supernatants by the adsorption chromatographic method and the catecholamine contents in the eluates were determined spectrofluorometrically. Protracted exposure to gamma radiation and hormonal stimulation with SG reduces the concentration of norepinephrine in the whole hypothalamus of the sheep. A statistically significant decrease (P less than 0.001) was recorded in the medial and caudal hypothalamus of the adult ewes and in the rostral and caudal hypothalamus regions of the young ewes. A decrease of norepinephrine concentration, statistically significant in the caudal (P less than 0.01) and medial hypothalamus, was recorded in the group of adult ewes after hormonal stimulation with SG without irradiation. The experimental group of young ewes responds to hormonal stimulation by a greater reduction of norepinephrine contents, as compared with combined exposure to radiation and hormonal stimulation. It is assumed that the decrease in catecholamine concentration after hormonal stimulation with SG is associated with the increase in the content of oestrogens, which act on the adrenergic receptors of the hypothalamus.

Adrenal Glands↗